A conventional steam cooker is disclosed in Patent Document 1. This steam cooker uses overheated steam as a heating medium, and has an article-to-be-heated placed on a tray arranged in a heating chamber. At a side of the heating chamber, a water tank is arranged, from which water is fed via a water feed passage to a steam generation device. The steam generation device has a steam generating heater, by which water is heated to generate steam.
The steam is blown out to a steam heating device that has a steam heating heater. The steam heating device heats the steam further by the steam heating heater to generate overheated steam, and then jets out the overheated steam to the heating chamber. The overheated steam jetted out to the heating chamber circulates to be heated by the steam heating heater, so that the overheated steam is maintained at a high temperature.
In this way, the article-to-be-heated is cooked under low-oxygen condition. As a result, it is possible to prevent oxidation of the article-to-be-heated, and to prevent generation of smell or deterioration in taste due to oxidized fat so as to perform satisfactory cooking. Moreover, fat contained in the article-to-be-heated melts and drips down along with water that has condensed from the steam, so that the article-to-be-heated is subjected to defatting, and thus healthy cooking can be performed.
In steam cookers for house hold use, there is a limitation on electric power that can be used, and electric power is supplied separately to the steam generation heater and to the steam heating heater. Overheated steam generated by the steam generation heater and the steam heating heater has a large latent heat, and condenses on the surface of the article-to-be-heated to permit its internal temperature to be raised quickly. In addition, by heat (radiation heat or hot airstream) from the steam heating heater, the article-to-be-heated is heated from its surface, so that, in addition to the internal temperature being raised, the surface of the article-to-be-heated is roasted brown.
For this reason, in a case where the supply of electric power to the steam generation heater is small, when the inside of the article-to-be-heated reaches an adequate temperature, the surface becomes scorched. On the other hand, in a case where the supply of electric power to the steam generation heater is large, when the inside of the article-to-be-heated reaches an adequate temperature, the surface is not roasted brown. Thus, the surface is not done crisp, and the taste is lost. Accordingly, cooking is performed with an appropriate electric power supplied to the steam generation heater and to the steam heating heater (for example, 260 W and 1040 W, respectively).    Patent Document 1: JP-A-2005-61816